i had some problems with stuck on Sony logo on differents Roms as well.Yesterday i was flashed ver. 5.02 Monx ROM and today ver.5.03.
I describe you, what i was doing,maybe it help (i had the problems too,but described procedere was succefull).
Once more-that is what i was doing,and at end i had MONX 5.03 up and running...
1.Flashed .534 ftf with flashtools (ver.0.9.15.0), ftf file was C6903_14.1.G.1.534_Commercial&Journalist_1277-1398.ftf, flash was at all default, as in flash guide.
2.Root .534 rom with rootkitZ1_14.1.G.1.534.Work super,no Chine stuff,reboot, SuperSU ist here (before install that -checked if USB-Debugging is on and allowed unknown apps in settings).
3.Install that recovery - "Z1-lockeddualrecovery2.7.101-BETA.installer". All was doing as in NUT recovery tread,after reboot in TWRP, just one time rebooted a phone.
4.Then reboot in TWRP, doing wile all (system,dalvik,cashe and data) and flashed file HONAMI_442_681_MONX_0503P_REL_AROMA.zip (before that double checked if md5 summ OK).After flash going to Reboot menu in TWRP and Turn Off a phone.
5.Start flashtools ver.0.9.15.0, use that full .ftf file - "C6903_14.3.A.0.681_Generic DE 1277-0154_R2C.ftf" (because i'm from Germany), in flashtool UNCHECKED all wipes and in exclude section only check system and TA for excluding.Flashed that file with those setting,at end maked sure,if a message about flash success is here,then unplugged a phone from PC.
6.Power On a phone,some short time it stay on Sony logo,the coming double vibration with LED-Ligh - it mean recovery is her,the phone boot up normally,
and voila - MONX 0503 is up and running-no FC (what i was checke till now)...
Sure optional - restored my data from previous TWRP backup.All worked OK as well...till now..
Wonderfull ROM!Thanks Monx for that!
Maybe it could helping you,many luck on that...
---------- Post added at 03:29 PM ---------- Previous post was at 03:27 PM ----------
Correct me if I'm wrong, but after you flash and root 534, don't you have to climb to 290 before moving on to 681? That's the process I did. 534, then root, then 290 and flash 290 stripped ftf by NUT. Then 681 and Stripped FTF by nut, and everything works like a charm.
I'll try the leap from 534 to 681 and see how it goes, i'll get it in the end it's just a pain in the backside.